From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.7.10) Gecko/20050720 Fedora/1.0.6-1.1.fc4 Firefox/1.0.6
Description of problem:
When I try to create a new locally connected device (hp:/net/hp_color_LaserJet_3550?ip=10.0.0.10), there's an error "hp:/net/hp_color_LaserJet_3550?ip=10.0.0.10 does not exist, or is not writable". Networked JetDirect queue type is not working as well.
It works in text mode selecting local printer device -> custom and setting the hp:/net/hp_color_LaserJet_3550?ip=10.0.0.10 parameter.
Version-Release number of selected component (if applicable):
system-config-printer-0.6.138-1-gui
How reproducible:
Always
Steps to Reproduce:
1. start system-config-printer-gui
2. add custom device with previously mentioned parameters
3.
Actual Results: It should work the same way in system-config-printer-gui as in the text version.
Additional info:

What does 'rpm -q system-config-printer' say? I'm a little confused, because
you seem to be indicating that you are running the Fedora Core development
version of that package, rather than the FC4 update.

rpm -q shows system-config-printer-0.6.138-1. It's my mistake, I tried to use
the latest version of SRPMS from rawhide (because the normal FC4 update produced
even worse results for me) and I recompiled it for FC4. I forgot to mention it.
I'm sorry :-(.

When I try to add new custom device (under locally connected queue type). There
is requester Enter the device you would like to use, so after filling that
device this error appears. It's possible to add this device with the same steps
in the text mode.

No, their are printers that it does not detect. In the readme for the source it
says they are aware of the problem and give directions for hp-makeuri. I have
an Officejet 7300. It is not found with hp-probe -bnet, and I can't find anyway
to add it via system-config-printer. I am using following packages:
hpijs-0.9.4-1.1, hplip-0.9.4-1.1, system-config-printer-0.6.131.3-1, and
system-config-printer-gui-0.6.131.3-1. After doing a hp-makeuri I am able to
add the device via the cups admin page, and then I can print, scan, and use the
photo card.